Automated electronics assembly machines are often used in the manufacture of printed circuit boards, which are used in various electronic devices. Such automatic electronic assembly machines are often used to process other devices that are similar to printed circuit boards. For example, the manufacture of photovoltaic cells (solar cells) often uses similar machines for printing conductive traces. Regardless of the substrate being processed, the process itself is generally required to operate quite swiftly. Rapid or high speed manufacturing ensures that costs of the completed substrate are minimized. However, the speed with which the substrates are manufactured must be balanced by the acceptable level of scrap or defects caused by the process. Printed circuit boards, for example, can be extremely complicated and any one board may have a vast number of small components and features and consequently a vast number of electrical connections. Furthermore, printed circuit board substrates may acquire a significant amount of warp as they progress through the various assembly steps. Since such printed circuit boards can be quite expensive and/or be used in expensive equipment, it is important that they be produced accurately and with high quality, high reliability, and minimum scrap. Unfortunately, because of the manufacturing methods available, some level of scrap and rejects still occurs. Typical faults on printed circuit boards include inaccuracy of placement of components on the board, which might mean that the components are not correctly electrically connected in the board. Another typical fault occurs when an incorrect component is placed at a given location on a circuit board. Additionally, the component might simply be absent, or it may be placed with incorrect electrical polarity. Further, other errors may prohibit, or otherwise inhibit, electrical connections between one or more components, and the board. Further still, if there are insufficient solder paste deposits, this can lead to poor connections. Additionally, if there is too much solder paste, such a condition can lead to short circuits, and so on.
In view of all of these industry demands, a need has arisen for automated optical inspection systems. These systems can receive a substrate, such as a printed circuit board, either immediately after placement of the components upon the printed circuit board and before wave soldering, or post reflow. Typically, the systems include a conveyor that is adapted to move the substrate under test through an optical field of view that acquires one or more images and analyzes those images to automatically draw conclusions about components on the substrate and/or the substrate itself. One example of such device is sold under the trade designation Flex Ultra™ HR available from CyberOptics Corporation, of Golden Valley, Minn. However, as described above, the industry continues to pursue faster and faster processing, and accordingly faster automated optical inspection is desired. Moreover, given the wide array of various objects that the system may be required to inspect, it would be beneficial to provide an automated optical inspection system that was not only faster than previous systems, but better able to provide valuable inspection data relative to a wider variety of components, substrates, or inspection criteria.